(a) Unlawful sexual intercourse is an act of sexual intercourse accomplished with a person who is not the spouse of the perpetrator, if the person is a minor. For the purposes of this section, a "minor" is a person under the age of 18 years and an "adult" is a person who is at least 18 years of age.

(b) Any person who engages in an act of unlawful sexual intercourse with a minor who is not more than three years older or three years younger than the perpetrator, is guilty of a misdemeanor.

(c) Any person who engages in an act of unlawful sexual intercourse with a minor who is more than three years younger than the perpetrator is guilty of either a misdemeanor or a felony, and shall be punished by imprisonment in a county jail not exceeding one year, or by imprisonment in the state prison.

(d) Any person 21 years of age or older who engages in an act of unlawful sexual intercourse with a minor who is under 16 years of age is guilty of either a misdemeanor or a felony, and shall be punished by imprisonment in a county jail not exceeding one year, or by imprisonment in the state prison for two, three, or four years.

(e) (1) Notwithstanding any other provision of this section, an adult who engages in an act of sexual intercourse with a minor in violation of this section may be liable for civil penalties in the following amounts:

(A) An adult who engages in an act of unlawful sexual intercourse with a minor less than two years younger than the adult is liable for a civil penalty not to exceed two thousand dollars ($2,000).

(B) An adult who engages in an act of unlawful sexual intercourse with a minor at least two years younger than the adult is liable for a civil penalty not to exceed five thousand dollars ($5,000).

(C) An adult who engages in an act of unlawful sexual intercourse with a minor at least three years younger than the adult is liable for a civil penalty not to exceed ten thousand dollars ($10,000).

(D) An adult over the age of 21 years who engages in an act of unlawful sexual intercourse with a minor under 16 years of age is liable for a civil penalty not to exceed twenty-five thousand dollars ($25,000).

(2) The district attorney may bring actions to recover civil penalties pursuant to this subdivision. From the amounts collected for each case, an amount equal to the costs of pursuing the action shall be deposited with the treasurer of the county in which the judgment was entered, and the remainder shall be deposited in the Underage Pregnancy Prevention Fund, which is hereby created in the State Treasury. Amounts deposited in the Underage Pregnancy Prevention Fund may be used only for the purpose of preventing underage pregnancy upon appropriation by the Legislature.

(3) In addition to any punishment imposed under this section, the judge may assess a fine not to exceed seventy dollars ($70) against any person who violates this section with the proceeds of this fine to be used in accordance with Section 1463.23. The court shall, however, take into consideration the defendant's ability to pay, and no defendant shall be denied probation because of his or her inability to pay the fine permitted under this subdivision.